Supercritical fluid extraction of bound pesticide residues from soil and food commodities

Zhu

Chemical Engineering Journal

2011

a b s t r a c tPolychlorinated biphenyls (PCBs) are environmentally persistent, toxic, bioaccumulative and recalcitrant. In this study, aged PCBs from e-waste contaminated site were respectively subjected to Soxhlet and solvothermal treatments. The results indicated that solvothermal method was much more predominant for PCBs removal than traditional Soxhlet method. Sequential Soxhlet-solvothermal experiment demonstrated that Soxhlet unextractable (bound) PCBs were efficiently removed by solvothermal procedure due to enhanced solvating effects of organic solvents. The key point was that bound PCBs in the aged soil were partitioned in different components of soil organic matter, e.g., the solvothermal removal amounts of I-V PCBs (sum of PCB8, PCB18, PCB28, PCB44, PCB66) from fulvic acid (FA), humic acid (HA), bound humic acid (bound HA), bound lipids and mineral fraction were 0.4, 40.8, 28.4, 19.8, and 10.6%, respectively. It was found that isopropanol was the most effective solvent for PCBs removal. The optimum performing temperature, time and liquid to solid ratio for PCB8, PCB18, PCB28, PCB44, and PCB66 were 170 • C, 8 h and 10:1, respectively. As for higher molecular weight PCB congeners, these conditions were 150 • C, 10 h and 15:1. Soil organic matter content was unchanged after solvothermal treatment indicating that soil fertility remained after the removal process. This work provides a more clean process for effective treatment of soils contaminated by persistent organic pollutants (POPs) in comparison to traditional methods.

Section: Predominance Of Solvothermal Processmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Advantage of solvothermal procedure for polychlorinated biphenyls removal from e-waste contaminated site

Zhu

Chemical Engineering Journal

2011

“…A l s o , methanol modified CO 2 e n abled the ex t raction of at ra z i n e, d e e t hy l at razine and deisopro py l atrazine from spiked sediment samples [23], while methanol containing 2% (v/v) water was efficient for atrazine and 2-hydroxyatrazine in a spiked soil (4% organic matter) [40]. However, more stringent conditions were required for bound residues; for example, 30% methanol was needed to effic i e n t ly ex t ract bound at razine from a mineral soil, a l o n g with high pressure (350 bar) and temperature (125°C) [56]. Another study rep o rted methanol or the mixture acetonewater-triethylamine (90/10/1.5 v/v/v) to enhance extraction of 2,4-D from soils [11,12,56].…”

Section: Soils and Sedimentsmentioning

confidence: 99%

“…However, more stringent conditions were required for bound residues; for example, 30% methanol was needed to effic i e n t ly ex t ract bound at razine from a mineral soil, a l o n g with high pressure (350 bar) and temperature (125°C) [56]. Another study rep o rted methanol or the mixture acetonewater-triethylamine (90/10/1.5 v/v/v) to enhance extraction of 2,4-D from soils [11,12,56].…”

Section: Soils and Sedimentsmentioning

confidence: 99%

“…Methanol has been widely used: extraction of dieldrin from radishes [56], chlorpyrifos from grass field samples [67], methamidophos from spiked vegetables [21], organophosphorus compounds from rice [68], carbendazime from lettuce leaves [69], fonofos from onions [56], pirimiphos methyl from wheat and beans [56], atrazine from canola [56]. Acetone was also efficient for the extraction of carbofuran and carbaryl from tobacco [70].…”

mentioning

confidence: 99%

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Supercritical fluid extraction as a useful method for pesticides determination

Camel¹

1998

Analusis

Despite attractive features (rapid extractions, small solvent volumes, non-toxicity of CO 2 , potential of selectivity depending on the fluid density, relatively clear and concentrated ex t ra c t s , p o s s i ble coupling with ch romatography and automation), the use of SFE in routine analytical ap p l i c ations is a rather slow process. Indeed, t h e major drawback of this recent technique is the large number of parameters to control and optimize, which results in time re q u i red for developing a new method. In add i t i o n , t h e extraction conditions are strongly dependent on the matrix to be extracted, so that parameters need to be adjusted for every new application. D e t e rm i n ation of pesticides remains a ch a l l e n ge fo r mainly three reasons: the wide variety of physicochemical properties and chemical structures of pesticides, the many possible matrices that should be investigated, and the trace c o n c e n t rations at wh i ch pesticides are usually pre s e n t . Recent papers reviewed environmental applications of SFE [1,2], especially with regards to the extraction of the main classes of pesticides [3][4][5]. As SFE perfo rmances are strongly dependent on the nature of the sample, this article will consider the matrices that have been submitted to SFE for pesticides determination. Principle of SFEA fluid is in its supercritical state when both its pressure and temperature are above their critical value (when only one c ritical value is at t a i n e d, the fluid is said subcri t i c a l ) . Supercritical fluids possess unique properties, intermediate between gas and liquids properties [6][7][8][9][10]. In particular, their high diffusivity allows for rapid extractions. In addition, the fluid density may be precisely adjusted, by a correct choice of both pressure and temperature.The key parts of an SFE system are the high-pressure pump wh i ch delive rs the fl u i d, and the re s t rictor wh i ch maintains the pressure inside the system. Extraction is performed inside a high-pressure cell (containing the sample), maintained at the correct temperature. The fluid may simply fill the cell (static mode), or continuously flow through the vessel (dynamic mode). The extracted solutes are entrained by the supercritical fluid flow out of the cell; their collection is usually achieved as the fluid is depressurized by passing through the restrictor. The collected solutes are further analyzed using gas or liquid chromatography. Also, a few recent studies report the use of enzyme immunoassay as a rapid screening process [5,11,12]. Alternatively, the SFE system may be coupled on-line with chromatographic systems, gas chromatography (GC), liquid chromatography (LC), or supercritical fluid chromatography (SFC), by means of an interface [5,8]. For example, the coupling of SFE and SFC e n abled the determ i n ation of thiolcarbamate herbicides (molinate and thiobencarb) from spiked soil samples (with organic content from 1.75 to 12.9%) [13]. Obviously, such a system seems very attractive when traces of pest...

Biomedical Chromatography

Development of a multiresidue method for the determination of multiclass pesticides in soil using GC

Park

Mamun

Choi

et al. 2010

The principal objective of the present study was to develop a multiresidue analytical method for 62 pesticides in a soil matrix. Soil samples were fortified with known quantities of pesticides at two different concentration levels (0.1 and 0.01 microg/g) and the analytes were extracted via a liquid-solid extraction method. The pesticides were separated on an HP5 capillary column and were detected by gas chromatography coupled to an electron capture detector (GC-ECD). The method was validated, considering its good linearities (r(2) = 0.978-0.999), specificity and recovery characteristics. Recoveries were found between 70.3 and 113.4% for all pesticides except edifenphos (67.5%) and dichlobenil (69.5%) spiked at a 0.1 microg/mL concentration level and 74.5-117% except ethalfluralin (63.3%) and dichlobenil (51.9%) spiked at a concentration of 0.01 microg/mL. The developed method could be utilized as a simple and cost-effective method for the routine analysis of 62 pesticides in soil samples.